Device for control and prevention of coast erosion



E. NIELSEN Nov; 10, 1970 DEVICE FOR CONTROL AND PREVENTION OF COAST EROSION Filed March 5, 1968 3 Sheets-Sheet l Fig.2

INVENTOR AV/ lie/re 0 E. NIELSEN 3,538,711-

DEVICE FOR CONTROL AND PREVENTION OF COAST EROSION Nov. 10, 1970 3 Sheets-Sheet 2 Filed March 5, 1968 INVENTOR $94.,

E. NIELSEN DEVICE FOR CONTROL AND PREVENTION OF COAST EROSION Filed March 5, 1968 3 Sheets-Sheet 5 United States Patent 3,538,711 DEVICE FOR CONTROL AND PREVENTION OF COAST EROSION Erik Nielsen, Frederikshavn, Denmark, assignor to Fyens Saelrkekompagni A/ S, Odense, Denmark Filed Mar. 5, 1968, Ser. No. 710,529 Claims priority, application Denmark, Mar. 7, 1967,

Int. Cl. E02b 3/12 U.S. Cl. 61-38 2 Claims ABSTRACT OF THE DISCLOSURE Effective seabed protection of coasts is achieved at low cost by perforated or pervious flexible tubes or hoses laid out in lengths and filled selectively with sand and small stones without any binding agents. Length of the tube is very large compared to the cross section filled to lie the same throughout its length. Since no hardeners are used, the filled tube is able to follow possible movements or changes in the seabed without showing any cracks. Seal ing of one end of the tube occurs and filling of at least a small length continues while progressively moving the tube or hose during the filling to place the same along the path where the coast protecting means is being deposited.

The invention relates to a device for controlling and preventing coast erosion and furthermore to methods of depositing the device.

For the purpose of protecting coasts, shores, riverbanks, breakwaters, dikes and the like against erosion various methods and devices have been suggested.

The suggestions could in the main be systematically divided into four groups.

The first group comprises construction of groynes. These can be constructed in various ways, for instance by placing concrete blocks of suitable sizes in a connected system or by placing stones between piles driven into the seabed. The drawback to groynes of the above type is, on account of their running above the water, that they break and bend the current. As a result very strong eddies arise, undermining and demolishing the groyne, partly by scouring at the extreme end of the groyne and partly by backwashing the shore connection of the groyne. Further a single groyne will give rise to erosion at a certain distance from the groyne as a result of the bend it imparts to the current. In addition, these groynes have very high construction costs and only relative short lives, cm. above, even where substantial amounts are spent on maintenance.

The second group concerns the efforts at stabilizing the seabed, for instance by means of placing foil on the seabed or by arrangement of underwater fascines. The drawback to these devices is their very short lives. Among other things, it has proved very difficult to secure foils on the seabed.

The third group comprises the efforts at reducing erosion through levelling and asphalting, etc. of dunes. These works are highly expensive and do not prevent the erosion, but merely delay it.

The fourth possibility is the placing of artificial seaweed. This solution appears efiicient, but has not yet been sufficiently tested on open shores.

3,533,711 Patented Nov. 10, 1970 In emergencies sandbags are used, especially for protection of dikes. Such sandbags are however heav to handle and will nevertheless be easily removed by the sea or be undermined and buried in the seabed.

Now it is an aim of the present invention to provide a device, which easily and for low costs can be laid to create an effective protection of coasts and the like. Another aim of the invention is to provide a device, where the above stated drawbacks do not appear.

According to the present invention the device comprises a length of a flexible preferably thin-walled tube or hose filled with a sandy and/ or stony material.

The tube or hose may be made of any suitable material, if just the requirement of flexibility is fulfilled,

Tubes of plastic may be used, for instance tubes of extruded plastic and also tubes of sheet plastic, supplied in length and welded to tubes on the location where they are used. If desired the sheets may be provided with reinforcements as known per se. As will later be more fully described, perforated tubes may be used.

Also tubes or hoses formed of woven or knitted materials come into consideration: manufacture from plastic threads, plastic filaments and other materials used for textile purposes including natural fibres and if desired reinforcement members which may be of mineralic origin, such as glass fibres.

When a length of such a tube or hose, filled with a sandy or stony material, is laid out on the seabed, it will adapt itself to the surface of the seabed. Due to the fact that the hose or tube is made without any transversal joints or bottlenecks and moreover is flexible, it will lie on the seabed with homogeneous contact rendering undermining difficult. If undermining should nevertheless occur to a limited extent under extreme conditions, the tube or hose will not be broken but will adapt itself to the new conditions.

The filled tube or hose may be laid as a single length, but may also be laid in two lengths side by side or in several lengths, where some of the lengths are superim posed underlying lengths.

For certain purposes the tube or hose may be designed with a particular cross section, such as in the form of a triangle, especially an equilateral triangle.

The design and size of the tube or hose section can be chosen to suit the conditions. If desired, the tube or hose may be formed with attached flaps or attached pockets to catch the movement of the sand of the seabed. Also artificial seaweed could be attached to the outside of the tube to influence the current, the effect of which causes the erosion.

The device according to the invention may be laid out transverse to the coastline, along the coastline, and due to the flexibility of the tube or hose also, if necessary, following any curved line.

The laying of the device can be eflected in short time and for low cost.

The invention also relates to methods of laying the above mentioned device.

One method according to the invention of laying the device comprises the steps of cutting the tube or hose to the length required, running a flexible pumping hose into the tilbe or hose, sealing the end of said tube or hose, which is to be laid first, anchoring this end to the seabed, keeping the rest of the tube or hose afloat, pumping a mixture of water and sand and/or pebbles into the tube or hose, gradually retracting the pumping hose, eventually sealing the tube when the filling has been completed.

If the walls of the tube or hose are unperforated the sand and/ or the pebbles pumped into it sediments therein, whereas the water of the mixture flows to the open end.

If the walls are perforated the water may pass out through the perforations. Some sand may also be carried out by the water through the perforations; this, however, is of minor importance due to the fact that sand is a cheap material and is easily accessible at coasts. Moreover it has been found that a large amount of sand particles being of a smaller size than corresponding to the mesh of the perforations is withheld inside the perforated tube, also when it has been lying on the seabed for months.

This also has been found if the sandy material used is a mixture of sand and clay particles. Only during the pumping clay particles will be carried out through the perforations, but when the tube has been filled and been situated on the seabed the clay particles will not be washed out.

Another method according to the invention of laying the device comprises the step of sealing one end of the tube or hose turning the tube inside out in such a way that on a small length from the sealed end the rest of the tube or hose is situated in a crimped position, filling said small length with a sandy and/or stony material and gradually, while still filling, turning the crimped part of the tube or hose back to normal.

Using this method the filling can be filled in either as it is, i.e. in dry state, or in wetted state or it can be filled in as a pumpable mass in a mixture with water.

Through this method it is possible to lay the device either from the coast and out into the sea or in the opposite direction.

A third method according to the invention comprises the forming of a tube from two or more rolls of sheet material filling the formed tube a small length from the site where the tube is formed.

The device according to the invention and the above mentioned methods for laying the device is not limited to the protection of coasts only, but could be used with advantage for the protection of dikes, by the construction of dikes, building of harbours and breakwaters, for damming, for changes of the courses of streams, etc.

In the following the invention will be further described with the aid of the drawings which by way of example only illustrate some embodiments of the invention.

In the drawing FIG. 1 shows a cross section of a tube.

FIG. 2 shows a longitudinal section of the tube of FIG. 1.

FIG. 3 shows a sectional elevation at right angles to a coastline, illustrating the principle of the laying of the tube.

FIG. 4 is a plane view of the arrangement shown in FIG. 3.

FIG. 5 shows the tube in similar way as FIG. 3 after completion of the laying operation.

FIGS. 6-8 show modified forms of tubes or hoses.

FIG. 9 shows a section of an apparatus for laying tubes according to a preferred method.

FIG. 10 a nozzle appearing in FIG. 9.

FIG. 11 a cross section of the nozzle according to FIG. 10.

FIG. 1 shows a cross section of the tube before laying. The section chosen is merely an example, which may be modified according to conditions. 1 is the tube wall. 2 is an example of a retaining device for the hose 3 to be used for pumping the filler into the tube. 4 is the surface of the water. 5 are the floats keeping the tube afloat, being connected with the tube by means of a line 6 and fastened by slip-sticks.

FIG. 3 is a schematic presentation of the laying operation, showing a sectional elevation at right angles to the coastline. The beach 7 passes into the seabed 8. The anchoring 9 is seen at the extreme end. Filling has been started, being effected from the shore in the example shown. Filling takes place at the vertical stage marked a between the floating and the submerged part of the tube.

FIG. 4 shows a plan view of FIG. 3. The innermost end of the tube is anchored on shore 10. In FIGS. 3 and 4 11 illustrates a pumping unit.

FIG. 5 shows the tube submerged. In this case the entire tube is submerged, but in the case of the tube having to be laid above water, for instance for damming purposes, generally speaking the same laying procedure can be applied.

FIG. 6 shows the cross section of a plastic tube 11, which may be formed either by extrusion or by welding a sheet of plastic. In the first case the welded parts form a flap 12. In the second case the flap 12 is formed during the extrusion. Small strips 12a of artificial seaweed are fastened to the flap.

FIG. 7 shows in perspective view a hose of woven polyethylene threads. The material is woven together at 13 and 14, whereby small flaps appear to the upper flap 14. Larger flaps 15 may be attached as indicated by dotted lines.

FIG. 8 shows in perspective view a hose of coarse woven material especially suited for filling with stony materials. The mesh of the woven material is so coarse that when small stones about up to mm. are filled in the hose, they may partly stick out of the holes. Such hoses are especially suited to be laid out on stony seabeds.

FIG. 9 shows diagrammatically a cross section of an apparatus suited for laying tubes of the form such as shown in FIGS. 6 and 7. 21 is a tube or hose, the ends of which have been sealed and stuck down through a nozzle 22, which is shown separately in FIG. 10. The nozzle comprises an upper funnel-shaped part 23, a lower funnel-shaped part 24 and a cylindrical connection part 25. The shown embodiment of the nozzle is built of rods. The outer diameter of the ring 26 is chosen so that the tube 21 may be turned inside out over the ring, whereas the diameter of the ring 27 has at least the same diameter as the tube to be laid, when the sealed end of the tube has been stuck down through the nozzle the rest of the tube is turned inside out over the ring 26 and sandy and/ or stony material filled in through the pipe 28. When the sealed end then sinks down, it runs along guiding rollers 29 and is deposited on the seabed.

30 and 31 are brackets supporting the nozzle in a desired angle A relatively to the seabed.

The brackets are fastened to a float or vehicle or still better to an amphibian vehicle to be universal usable. When using a tube of 800 mm. diameter and a nozzle 1200 mm. long, it is possible to have meters of tube stored on the outside of the nozzle.

What I claim is:

1. A method of laying a coast protecting device com-' prising at least one length of a flexible preferably thinwalled pervious tube or hose filled selectively with a sandy, stony material, comprising the steps of cutting the tube or hose to a length required, running a flexible pumping hose into the tube or hose, sealing the end of the tube or hose, which is to be laid first, anchoring this end to the seabed, keeping the rest of the tube or hose afloat, pumping a mixture of water and selectively sand and pebbles into the tube or hose, gradually retracting the pumping hose, eventually sealing the tube when the filling has been completed.

2. A method of laying a coast protecting means comprising at least one length of a flexible preferably thinwalled pervious tube or hose filled selectively with a sandy, stony material, comprising the steps of sealing one end of the tube or hose, turning the tube inside out in progressively moving the tube or hose during said filling to place the same along the seabed path where the coast protecting means is being deposited.

References Cited UNITED STATES PATENTS 1,275,860 8/1918 Cunningham 61-38 1,783,908 12/1930 Hebden 68-198 6 Wicklander 61--1 Ionides 6137 X Nielsen 613 Jennings et al.

Lamberton 61-38 Hillen 6138 DAVID J. WILLIAMOWSKY, Primary Examiner 10 P. c. KANNAN, Assistant Examiner 

